Biological specimens are tested for a wide variety of reasons. For example, immunohistochemical (IHC) assays and assay techniques based on in situ hybridization (ISH) and, in particular, fluorescent in situ hybridization (FISH) are commonplace techniques used in medical diagnostics today. Biological samples such as tissue or cell samples from suspected or known diseased patients are analyzed using IHC and ISH/FISH techniques to determine or monitor the patient's status with respect to the disease under investigation. However, both IHC and ISH/FISH methods require the performance of numerous complex and time consuming steps in preparing the tissue and cell samples and then carrying out the actual IHC or hybridization assay. When performed manually, these assay methods are tedious, technically demanding and time consuming. Nevertheless, well-established protocols have been established for manual assays. FISH is also discussed in U.S. Patent Publication No. US 2007/0048770 A1, the full disclosure of which is hereby incorporated by reference.
According to common FISH protocols, glass slides may be pre-treated with protease in order to digest cellular proteins that could interfere with DNA hybridization, with protease treatment consisting of a series of steps followed by ethanol dehydration. Additional sample fixation is also required in most cases.
Hybridization and denaturation steps are typically carried out at elevated temperatures that result in evaporation of assay reagents. To prevent excess evaporation, the sample specimens are typically covered on the slides by cover slips sealed around the edge by rubber cement.
Following hybridization, nonspecifically bound probe is washed off the sample, and then DNA is counter-stained with DAPI. However, to accommodate the post-hybridization wash, the rubber cement is peeled off manually to free the cover slip from the slide. The slides can then be immersed into a wash solution to complete the wash.
With the increased volume of testing, automated systems have been increasingly required, particularly for labor intensive procedures and time consuming protocols. Such systems not only increase reliability through consistent performance of required actions, but also reduce labor costs not only by freeing technicians from having to perform particular steps but also by allowing actions to be taken without requiring intervention by technicians (e.g., with time consuming protocols, actions can take place overnight without requiring that a technician be at the laboratory overnight to perform such actions).
However, while various automated systems have been developed to facilitate the processing of FISH assays, not all procedures required in an assay have heretofore been capable of being performed by those automated systems. For example, specimen slides prepared with rubber glue sealing around the edge of the cover slips are not readily adaptable to use in automated systems where the required process involves removal of the cover slip. The rubber glue prevents the automated systems from being able to reliably grasp and remove the cover slip, both by potentially interfering with the necessary contact of the apparatus with the cover slip and by securing the cover slip so securely to the slide that the automated system is unable to apply a sufficient force to pull the cover slip off.
The present invention is directed toward overcoming one or more of the problems set forth above.